A Model for Post-Occlusive Reactive Hyperemia as Measured With Laser-Doppler Perfusion Monitoring

Mul, F.F.M. de; Morales, F.; Smit, Andries J.; Graaff, Reindert

doi:10.1109/tbme.2004.840507

Cited by 32 publications

(43 citation statements)

References 11 publications

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“…As can be seen from Figure 11 the frequency of the signal has increased from 0.16 Hz prior to the occlusion to -0.26 Hz post occlusion in the example given, with some change in the magnitude of the phase measurement. As with a post-occlusive reactive hyperemia test it was noted that stabilisation to a the pre-test condition took a number of minutes [25] this is due to the time taken to normalise the O 2 , CO 2 , NO and metabolites in the tissues after restoration of blood flow. We are currently investigating the utility of this new metric as we are able to observe a measurable effect in tissue in vivo.…”

Section: Occluded Blood Flowmentioning

confidence: 99%

Wearable Multimodal Skin Sensing for the Diabetic Foot

2016

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Ulceration of the diabetic foot is currently difficult to detect reliably in a timely manner causing undue suffering and cost. Current best practice is for daily monitoring by those living with diabetes coupled to scheduled monitoring by the incumbent care provider. Although some metrics have proven useful in the detection or prediction of ulceration, no single metric can currently be relied upon for diagnosis. We have developed a prototype multivariate extensible sensor platform with which we demonstrate the ability to gather acceleration, rotation, galvanic skin response, environmental temperature, humidity, force, skin temperature and bioimpedance signals in real time, for later analysis, utilising low cost Raspberry Pi and Arduino devices. We demonstrate the utility of the Raspberry Pi computer in research which is of particular interest to this issue of electronics-Raspberry Pi edition. We conclude that the hardware presented shows potential as an adaptable research tool capable of gathering synchronous data over multiple sensor modalities. This research tool will be utilised to optimise sensor selection, placement and algorithm development prior to translation into a sock, insole or platform diagnostic device at a later date. The combination of a number of clinically relevant parameters is expected to provide greater understanding of tissue state in the foot but requires further volunteer testing and analysis beyond the scope of this paper which will be reported in due course.

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Section: Occluded Blood Flowmentioning

confidence: 99%

Wearable Multimodal Skin Sensing for the Diabetic Foot

2016

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“…To select the time-domain parameters of reactive hyperemia, the down-sampled SBF signal was processed with a 10th order Chebyshev I low-pass filter (cutoff frequency 0.15 Hz) to eliminate the blood flow oscillation caused by heart rate and respiration; the signal then underwent a median filter (22-second window) to remove the artifacts of the signal caused by involuntary movement/spasticity of the subjects with SCI. To select the parameters objectively, the modified bi-exponential equation 23 was used to fit the reactive hyperemic response on the SBF signal. A least-squares model fit was used to fit the bi-exponential curve…”

Section: Data Collection and Processingmentioning

confidence: 99%

Effectiveness of local cooling for enhancing tissue ischemia tolerance in people with spinal cord injury

Tzen¹,

Brienza²,

Karg³

et al. 2013

The Journal of Spinal Cord Medicine

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Objective: To investigate the effects of localized cooling and cooling rate on pressure-induced ischemia for people with and without neurological deficits. Design: A 2 × 3 mixed factorial design with two groups: (1) people with spinal cord injury (SCI) and (2) people without neurological deficits (control), and three test conditions: (1) pressure only, (2) pressure with fast cooling (−4°C/min), and (3) pressure with slow cooling (−0.33°C/min). Setting: University laboratory. Participants: Fourteen controls and 14 individuals with SCI. Interventions: Pressure on the sacrum was 0.4 kPa for 5 minutes, then 8 kPa for 20 minutes, and finally 0.4 kPa for 15 minutes. Fast and slow cooling to 25°C applied during 8 kPa of pressure. Outcome measures: Reactive hyperemia and its spectral densities in the metabolic, neurogenic, and myogenic frequency ranges. Results: In controls, reactive hyperemia was greater in pressure only as compared with both cooling conditions. No change was noted in all spectral densities in both cooling conditions, and only neurogenic spectral density increased without cooling. In subjects with SCI, no difference was noted in reactive hyperemia among conditions. However, metabolic and myogenic spectral densities increased without cooling and all spectral densities increased with slow cooling. No change was noted in all spectral densities with fast cooling. Conclusion: Local cooling reduced the severity of ischemia in controls. This protective effect may be masked in subjects with SCI due to chronic microvascular changes; however, spectral analysis suggested local cooling may reduce metabolic vasodilation. These findings provide evidence towards the development of support surfaces with temperature control for weight-bearing soft tissues.

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“…In this field, the non-invasive vascular reactivity test, called postocclusive reactive hyperaemia (PORH) gained attention. This procedure is based on the ability of the endothelium to release vasodilator agents like nitric oxide (NO) as a response to proximal arterial occlusion [9]. After occlusion, when the peripheral perfusion (PP) is restored, flow is increasing because of the reduced vascular resistance.…”

Section: Introductionmentioning

confidence: 99%

Assessment of Post-Occlusive Reactive Hyperaemia in the Evaluation of Endothelial Function in Patients with Lower Extremity Artery Disease

Carasca

Magdás

Ţilea

et al. 2017

Acta Medica Marisiensis

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Background:The aim was to assess endothelial function with photoplethysmography (PPG), by post-occlusive reactive hyperaemia (PORH) combined with alprostadil challenge test in patients with peripheral artery disease (PAD). Methods: Forty-nine PAD patients stage II-III Fontaine (39 male, 10 female, mean age 68.45±5.86 years) and a control group of 49 healthy individuals (24 male, 25 female; mean age 25.1±3.8 for a young subgroup; 71.0±0.16 years for an elderly subgroup) were included. Ankle-brachial index (ABI) was assessed at baseline, peripheral perfusion (PP) and PORH were assessed at baseline and after the 30 minutes administration of parenteral alprostadil. Results: After 3 minutes of arterial occlusion, peripheral perfusion increased from 0.69±0.94 mV/V to 2.27±2.42 mV/V (p<0.0001). After alprostadil challenge, peripheral perfusion increased from 0.84±1.24 mV/V to 4.52±3.52 mV/V (p<0.0001). In controls PP was 2.4±1.7 mV/V versus 3.8±1.5 mV/V, p<0.0001. Conclusion: In patients with PAD, an increase in PORH after alprostadil challenge due to the release of nitric oxide (NO), provides information on the endothelial function and could reflect the presence of collaterals. In the healthy control group, the increase in PORH could reflect the integrity of main arterial branch. In PAD patients with an increase in PORH, conservative therapy should be preferred over surgical revascularisation.

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A Model for Post-Occlusive Reactive Hyperemia as Measured With Laser-Doppler Perfusion Monitoring

Cited by 32 publications

References 11 publications

Wearable Multimodal Skin Sensing for the Diabetic Foot

Wearable Multimodal Skin Sensing for the Diabetic Foot

Effectiveness of local cooling for enhancing tissue ischemia tolerance in people with spinal cord injury

Assessment of Post-Occlusive Reactive Hyperaemia in the Evaluation of Endothelial Function in Patients with Lower Extremity Artery Disease

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